Transfer film, coating system and method for transferring images onto substrates

Abstract

The present invention relates to a transfer foil for transferring images onto solid substrates (transfer printing), such as textile supports, in particular T-shirts, metallic supports or plastic, in particular signs, ceramic supports, in particular cups and plates, etc., comprising a two-dimensional carrier based on polyester, based on polyether ether ketones or based on a cellulose-based material, having a layer (a) which is arranged on at least one of the carrier surfaces and which is made of a cross-linked, at least partially hydrolysed polyvinyl alcohol (PVA) polymer, The present invention also relates to the use of same. A further subject matter of the present invention is a ready-to-use system for transfer printing, comprising a transfer foil and an image applied thereto, in particular printed thereon, and a hot melt adhesive.

1 . Transfer foil for transferring images onto substrates, comprising a two-dimensional carrier based on polyester, based on polyether ether ketones or based on a cellulose-based material, having a layer (a) which is arranged on at least one of the carrier surfaces and which is composed of a cross-linked, at least partially hydrolysed polyvinyl alcohol (PVA) polymer. 
     
     
         2 . Transfer foil according to  claim 1 , wherein the PVA polymer in the uncrosslinked state has a degree of hydrolysis of about 72-99 mol %, preferably about 72-95 mol %, particularly preferably about 72-90 mol %, more preferably about 72-85 mol %, in particular about 72.5-75 mol % and a viscosity of about 2.5-55 mPa·s, preferably about 3.5-35 mPa·s, particularly preferably about 4-10 mPa·s. 
     
     
         3 . Transfer foil according to  claim 1 , wherein one or more crosslinking agents selected from the group containing glutaraldehyde, glyoxal, maleic acid, fumaric acid, malic acid, sulfosuccinic acid, phthalic acid, isophthalic acid, terephthalic acid, aconitic acid (cis, trans), citric acid and boric acid and the salts thereof, borates and hexamethylene diisocyanate, preferably maleic acid, fumaric acid, malic acid, sulfosuccinic acid, phthalic acid, isophthalic acid, terephthalic acid, aconitic acid (cis, trans), citric acid and boric acid and the salts thereof and optionally one or more co-crosslinking agents selected from melamine/formaldehyde resins and 3-aminopropyltriethoxysilane are incorporated by polymerization into the PVA polymer. 
     
     
         4 . Transfer foil according to  claim 1 , wherein the crosslinked PVA polymer has cationic characteristics. 
     
     
         5 . Transfer foil according to  claim 1 , wherein additionally cationic promoters are incorporated by polymerization into the PVA polymer, preferably selected from starch, polyamines, metal complexes, cationically modified silicic acid and salts. 
     
     
         6 . Transfer foil according to  claim 1 , wherein additionally one or more components which are incorporated by polymerization into the PVA polymer, selected from the group including additives for setting the porosity, wetting agents, additive for adjusting the viscosity, matting agents, additives with anionic functionality, pigments and processing aids are used. 
     
     
         7 . Transfer foil according to  claim 1 , wherein the layer (a) has a layer thickness of about 1-15 g/m 2 . 
     
     
         8 . Transfer foil according to  claim 1 , wherein a plurality of, preferably two, layers (a) of the same or different composition are arranged one above the other. 
     
     
         9 . Transfer foil according to  claim 1 , having a further layer (b) on the layer (a), wherein the layer (b) is composed of one or more waxes. 
     
     
         10 . Transfer foil according to  claim 9 , wherein the wax is selected from carnauba wax, jojoba wax, candelilla wax, rice bran wax, beeswax, whalebone and a mixture thereof. 
     
     
         11 . Transfer foil according to  claim 9 , wherein the layer (b) contains one or more additional components, selected from the group containing release agents, cationic promoters, film formers, silicic acid, optionally organically modified, pigments and processing aids. 
     
     
         12 . Transfer foil according to  claim 9 , wherein the layer (b) has a layer thickness of about 1-15 g/m 2 . 
     
     
         13 . Transfer foil according to  claim 9 , wherein a further layer is arranged over the layer (b), preferably a layer (a). 
     
     
         14 . Transfer foil according to  claim 13 , wherein the further layer (a) has the same composition as the layer (a) arranged directly on the carrier surface. 
     
     
         15 . Transfer foil according to  claim 8 , wherein the layer (a) is free of citric acid. 
     
     
         16 . Transfer foil according to  claim 1 , wherein the carrier is an uncoated foil. 
     
     
         17 . Transfer foil according to  claim 1 , wherein the carrier is a biaxially oriented polyester foil (BO-PET). 
     
     
         18 . Transfer foil according to  claim 1 , wherein the carrier surface is subjected to an electromagnetic treatment, preferably selected from plasma treatment or corona treatment. 
     
     
         19 . Ready-to-use system for transfer printing, comprising a transfer foil according to  claim 1  having an image applied onto the layer (a) or, if present, onto the layer (b) and a heat-treated hot melt adhesive applied onto the image. 
     
     
         20 . System according to  claim 19 , wherein the image is applied with the aid of a CMYK inkjet printer, additionally using the colour white. 
     
     
         21 . System according to  claim 19 , wherein the transfer printing is carried out according to the direct-to-film (DTF) technology.